Filtration systems of carbon dioxide (CO2) via chemical absorption can harness the organic energy potential of CO2 by decreasing or eliminating its emission into the atmosphere and utilizing it safely for alternative means. Methods of using available energy sources to absorb CO2 from the atmosphere, from industrial flue gas and from motor vehicle exhaust emissions for carbon fixation are described here. Waste carbon and combustion products are chemically treated to form useful materials which contain CO2 in a solidly fixed state, harmless to the environment. One such material is a CO2-contained adhesive.
The burning of biomass and fossil fuels continually increases greenhouse gas concentrations in atmospheric air. In particular, the greenhouse gas carbon dioxide is one of the most substantial contributors to the significantly increasing proportions of these gases in the air. These anthropogenic CO2 contributions to the atmosphere have increased 100 parts per million (ppm) since the Industrial Revolution. Current global CO2 levels are about 365 ppm.
Public and scientific communities now focus on the potentially dangerous effects of CO2-induced climate change. Atmospheric measurements indicate a continuous annual increase of CO2 in the middle layers of the troposphere. This research, conducted by Keeling and Whorf, at the Scripps Institute of Oceanography, Mauna Loa Observatory in Hawaii, produced the longest-ever continuous recording of CO2 readings in the atmosphere. Their records indicate a 19.4% (mean) annual increase from 1958 to 2004.
In addition to global warming cycles largely attributed to this heat blocking molecule, recent studies of oceanic acidification from CO2 absorption indicate a steady lowering of normal off-shore pH values and provide evidence for upwelling of acidified water onto the western North American continental shelf. In a 2008 article in Science, Feely, et al, show the negative effects of this acidification on marine animals by reducing their rate of calcification.
Attempts to mitigate carbon emissions today include wet scrubbers at coal-fired power plants and catalytic converters on motor vehicles. These methods, as well as others, adopted in the United States for decades, do work. The exception, however, is that they indicate moderate effects, and they only treat emissions at the point of production. Effectiveness in carbon control is a key requirement for international acceptance standards for motor vehicle emissions and industrial pollution control technologies worldwide.
While significant work is needed to evolve source-driven solutions, new open air carbon capture methods are also required as the greenhouse problem and its effects grow and become more significant with time. Here, we disclose several embodiments of methods for both carbon capture and storage in both cases.
According to one aspect of the present invention, in the case of motor vehicles, an active chemical CO2-control device takes advantage of the engine-derived pressure pulses exiting from stock exhaust systems. The pressure pulses either increase or decrease in their frequency corresponding with the engine's revolutions per minute (RPMs). To keep the exhaust flowing freely and preventing unwanted restrictions, the CO2 control device is designed to directly push exhaust straight through with minimal to no interruptions. The toroidal exhaust energy is received by the CO2 absorption material along the cylinder wall of the flow-through apparatus. Each pulse of energy-containing combustion gases contacts the packing material, and discharges a portion of pollutants with each event.
The packing material in the expansion chamber is a high temperature ceramic woolen matrix containing silicon. It is treated with a mild alkaline and held in place by a smoothly louvered stainless steel insert, which separates the flow path from the filter. A pH indicator in the filter housing subsequently reads the changing acidic values after CO2 saturation. Spent filter packing material can be recycled and the replacement filters are easily installed and snap back into the chamber. Filter life is short and can be measured out in months. The amount of CO2 captured by each filter can also be measured easily for carbon credits and/or rebate systems.
The filter, now containing CO2 and other contaminants, is then chemically processed to prevent sequestering storage problems and potential problems in the future from CO2 re-entering the earth's systems: biosphere, geosphere, atmosphere, etc.
According to other aspects of the present invention, Carbon dioxide filtration systems from chemical absorption are powered by wind, wave, pressure, solar, and convection. They share similarities in that they carry potential for creating alternative energy sources when combined with off-the-shelf, readily available materials and products. The structures, comprised of conduits of ‘forced air’, contain carbon dioxide for additional carbon-extraction processes. Furthermore, the captured carbon is used to assemble a useful material.
In certain known technology for treating high concentrations of carbon in flue stack emissions, the carbon is first absorbed by water and a weak, basic hydroxyl solution in a short-term process. This reaction is established and common. A weak solution of aqueous sodium or potassium hydroxide alters when the slightly basic regime increases in acidity as the CO2 rapidly absorbs from the air. Then, by addition of calcium hydroxide, a calcium carbonate solid precipitate forms due to the presence of CO2 now in solution.
In an effort to reduce energy requirements, and according to one aspect of the present invention, a cleaner alternative process for CO2 collection is achieved by precipitating calcium carbonate directly by mixing an aqueous solution of calcium chloride (CaCl2) with an aqueous solution of sodium hydroxide (NaOH).CO2(g)+H2O(aq)⇄H2CO3(aq)
In the reaction above, equilibrium is established between the dissolved carbon dioxide and carbonic acid. Subsequently, carbonic acid dissociates in two steps:H2CO3⇄H++HC03−(hydrogenated biocarbonate ions), then HCO3−⇄H++CO32−⇄(carbonate ions)
Adding aqueous calcium hydroxide, Ca(OH)2 (aq), to the calcium ion, Ca2− (aq), plus the carbonate ion CO32− (aq), produces:H2CO3(aq)+2KOH→K2CO3+2H2O3,or by using potassium hydroxide as substitute:K2CO3 or Na2CO3+Ca(OH)→CaCO3(s) (calcium carbonate precipitate)+2NaOH (or KOH).
The collected CO2 with calcium carbonate is further processed by the addition of ground pozzolana, a volcanic ash originally used by the Romans, which is composed of siliceous and aluminous material from the Mount Vesuvius region in Pompeii, Italy.
The application here, for a similar glassy beaded waste material, such as common fly ash, is to capture CO2 and form a useful product which contains CO2 in a solidly fixed state—harmless to the environment. The CO2 adhesive material, as disclosed, contains cement-like properties. The precipitate CaCO3 (limestone) plus a volcanic ash (used instead of sand) eliminates the energy wasteful, high-temperature process of formulating conventional cement. The heating step required for manufacturing generic cement results in a massive release of CO2 into the atmosphere. With volcanic ash, nature has already provided the heat.
Limestone/carbon dioxide slurry in combination with a clay-like volcanic ash hardens under water. Either fresh or salt water will yield similar results. The chemistry of combining pozzolana with limestone has been previously described by the Roman Emperor Augustus in the 5th Century BC.
According to still further aspects of the present invention for low concentrations of carbon in remote locations, atmospheric air-trapped CO2 is reclaimed continuously. Calcium carbonate precipitates by mixing an aqueous solution of calcium chloride (CaCl) with an aqueous solution of sodium hydroxide (NaOH) for trapping CO2 over time. Wind-driven venturi structures, a consequence of Bernoulli's principle, involve air flow entering into constricted sections of tubing at points where velocity increases and pressure becomes sub-ambient. Conversely, as tube diameters expand, pressure increases as air flow velocity slows. Similar reaction vessels follow the venturi model and take advantage of wind and wave energy.
In the case of wave power, there are several categories already developed which generally are location-dependent and used in generating electricity. For example, one method for shoreline operation is the oscillating water column.